ICD-10-CM > E00-E89 > E20-E35 > E34 > E34.0 E34.0 Carcinoid syndrome Non-Billable/Non-Specific Code Also the underlying disorder, such as:primary neuroendocrine tumors (C7A.-)secondary neuroendocrine tumors (C7B.-) Codes E34.00Carcinoid syndrome, unspecifiedE34.01Carcinoid heart syndromeE34.09Other carcinoid syndrome